Question

The intensity of a lightbulb with a resistance of 160 ohms is
controlled by connecting it in series with an inductor whose
inductance can be varied from L = 0 to L sub max. This "light
dimmer" circuit is connected to an ac generator with a frequency of
50.0 Hz and an rms voltage of 120 V .

Part A: What is the average power dissipated in the lightbulb when
L = 0 ?

Part B: The inductor is now adjusted so that L = L sub max. In this
case, the average power dissipated in the lightbulb is one-fourth
the value found in part A. What is the value of L sub max?